Method and means for the recordation duplication and reproduction of sound and pictorial images



Sept. 22, 1936.

METHOD AND MEAfis L. OSWALD ET AL FOR THE RECORDATION DUPLICATION AND REPRODUCTION OF SOUND AND PICTORIAL IMAGES Original Filed Oct. 29, 1923 2 Sheets-Sheet l I Eg.2

I l- I i II I x l' 54 i I 4J- I P -4 1 I 44"", l I 4 I 4 I I 3 64 I /Z 4 x l INVENTORS 04%4 100/0 0.? W440 BY Sept. 22, 1936.

c. L. OSWALD ET AL 2,055,261 METHOD AND MEANS FOR THE RECORDATION DUPLICATION AND REPRODUCTION OF SOUND AND PICTORIAL IMAGES 2 Sheets-Sheet 2 Original Filed Oct. 29, 1928 INVENTORS. C, a Lows- Oawxmo WA/PRf/V DUN/1AM 0$7E/P Wm B.

ATTORNEY.

Patented Sept. 22, 19 36 UNiTED STATES 2,ii55,26l

PATENT OFFICE .METHOD AND IMEANS FOR THE RECORDA- TION DUPLECATION AND REPRODUCTION OF SOUND AND PIGTOREAL WAGES Original application October 29, 1928, Serial No. 315,761. Divided and this application August 21, 1933, Serial No. 686,155. In Great Britain October 26, 1929 17 Claims.

The present invention relates broadly to the art of recording sound upon light sensitive material and the reproduction of sound therefrom by photo-electrical means, but it will be readily 5 understood that it may be applied to many other uses. Our invention is particularly applicable to so-called film-playing phonographs, both for initial recordation and subsequent reproduction, particularly with films which carry sound images in conjunction with visual images, as in the socalled talking movies. Our invention also includes the method, and means for the production, of duplicate sound records, or positive prints from a master record or negative, for combination with pictures or use synchronously therewith, such method and means being useful steps in the accomplishment of the final result of improved tonal and pictorial reproduction.

The present application is divisional from our co-pending application, Serial Number 315,761, filed October 29, 1928, and allowed May 25, 1933, which upon September 26,- 1933, matured as Patent Number 1,928,392, and relates primarily to the joint recordation, duplication and reproduction of both sound and pictorial images.

A primary object of our invention is to secure the accurate and faithful translation of sound waves into photographic images and of the resulting photographic images into sound waves. We provide improved method and means whereby recorded sound may be reproduced more accurately and pleasurably than heretofore has been possible in conjunction with pictures. A related object is the photographing upon film from which sound is to be reproduced, preferably concurrently with the photographing thereupon of the pictorial images, of lines or masses which are so clear and distinct, and of such uniform density, that sound waves reproduced from them will be clear, distinct and true. We also provide a method for the translation of these reproducing lines, masses or signals into audible sound waves, which reduces to a minimum any possibility of 45 distortion or blurring, such translation taking place concurrently with the projection of the pictorial images. In our parent application, to which reference is made above, we-describe and claim similar method and means applied to the initial recordation, subsequent duplication, and final reproduction of sound images alone.

A principal object of our invention is the provision of method and means whereby in a film carrying sound and pictorial images, the quality of neither will be sacrificed to the demands of the other, but both sound and picture will be presented accurately and pleasingly.

Another object of our invention is to make possible the use of photographic images in lines or mass formations, representing sounds which it is desired to record or reproduce, which photographic images may be materially smaller than such as now are common in the art and hence of particular usefulness in connection with motion picture films of 16 millimeters or 9 millimeters in width or of some other size primarily designed for home use and which are of less than the so-called theatrical standard of 35 millimeters width. Obviously upon such films, which because of economy and other commercial conditions, are now well established for domestic use, the area which is available for the sound image is very much reduced. As a consequence the difficulties which have arisen from ill defined photographic images, representing sound impulses, when these are imprinted upon 35 millimeter films, have been greatly exaggerated when such images have been correspondingly reduced in size for use upon the small area of the 16 millimeter or other so-called substandard film which can be taken from the area devoted to the pictures. Our invention makes it possible to sesure' upon 16 millimeter film, for example, as clear and accurate sound-images-as those which previously have been secured upon millimeter 35 film, and applies with corresponding efiect to film of even smaller dimensions.

Another object of our invention is the reproduction of duplicate copies or prints of combined sound and picture films in which the picture record is printed in accordance with the photographic requirements of the sound record, thus making it possiblein a single operation, for example, to printthe pictorial portion very soft with a minimum of contrast and the sound portion very hard with a maximum of contrast, thus much improving the quality of the reproduction,

, audibly and visibly, of the combined sound and pictorial record.

Another object of our invention is to add to the electrical acoustic means commonly employed in the initial recordation, subsequent duplication and final reproduction of sound images certain photographic methods, means, and technique in such manner as to secure improvement in the quality of sound translation and retranslation, and at the same time to permit iull liberty in the handling of the pictorial image. By

the employment of the apparatus and the meansand methods herein described, it is possible to assure the integrity of the latent sound image as of the moment at which it is implanted upon the photo-sensitive material without in any way sacrificing the quality of the accompanyingpictures. A further object of our invention is the treatment of that latent image by such chemical and physical means, chosen with due regard to the means and methods which had been employed to implant the latent image and the characteristics of the particular photo-sensitive material employed, as will retain in the stable and completed sound image the quality imparted by such previous steps in the process, likewise without injury to the pictorial image.

Another object of our invention is to provide apparatus for the taking, printing and projecting of talking pictures, which may be simply constructed and maintained, and a method which is simple and inexpensive.

Other objects, advantages and characteristics of our invention are apparent from the following description, the attached drawings and the subjoined claims. Although we are showing one preferred embodiment of each of the several phases of our invention, it will be' readily understood that we are not limited to these particular constructions and processes as changes can be readily made without departing from the spirit of the invention or the scope of our broader claims.

It will be readily-understood by those skilled in the art that our invention applies to sound apparatus generically. It will also be readily understood that our invention may be applied to any art in which the accurate and controlled recordation of a photographic image is useful or necessary in the exercise of control or translation by means of light.

In the drawings:

- Figure 1 is a diagrammatic representation of diflractlon occurring as light passes through an aperture, greatly exaggerated for the purpose of clarity.

Figure 2 is a diagrammatic section along the Surface IIlI of the film of Figure 1.

Figure 3 is a diagrammatic view of one form of our invention as embodied in a sound recording instrument.

Figure 4 is a diagrammatic view of one form of our invention as embodied in a sound reproducing instrument.

Figure 5 is a diagrammatic representation of an aperture plate and gate which we may use as a common gate, for both series of images.

Figure '6 shows our invention applied to an optical reduction printer with a common gate for both pictorial and sound images.

Figure 7 shows means employed by us to maintain a light source at a constant temperature and point of incandescence.

Throughout the drawings and specifications, like characters apply to like parts. For the purpose of greater simplicity, like parts which are duplicated in various embodiments of our invention receive the same reference numerals except where clarity demands otherwise.

In carrying out our invention, we employ light ages for use as sound records.

of a predetermined wave length. We select light of that particular rate of vibration which has the photographic qualities which are desirable tor the particular result which is to be obtained. For example, when we select light from the visible spectrum, we employ monochromatic light of a selected color or wave length, for the recordation of the photographic image representing the the particular emulsion deemed most suitable.

We select the developer for the latent image so implanted upon the selected emulsion by use of light of a selected wave length with due regard both to the particular characteristics 01 the particular emulsion and its reaction to the selected wave length and also to the peculiar demands of that portion of the film bearing the pictorial image as well as ofthat portion of the film bearing the sound image, in case both images are at once or ultimately implanted upon the same strip. Thus it will be seen that we choose that particular combination of light, emulsion, and developer which will result in the most satisfactory sound and pictorial images under the given conditions. v

In present common practice, polychromatic light, ordinarily spoken of as white light, is employed in apparatus using visible light for the electrical recordation of sound. Even with the use of a better photographic technique than is now common," polychromatic light would still cause many of the difliculties to which reference has already been had and will later be made.

For purposes entirely difierent from those embraced within or pertinent to our invention, it has been proposed to employ visible colored im We do not use colored images as part of or in carrying out our. invention of sound recordation. We use what is ordinarily known as colored light, but the latent images produced thereby, when rendered stable and visible by development, are what are known as black and white. They have none of the characteristics, requirements or purposes of colored images or photography. It will therefore be understood by those skilled in the art, that our invention does not require the use of the special and expensive films and apparatus, which have been proposed to be used for purposes different from our own, nor are we limited by the many photographic and practical difiiculties associated with the use of so-called colored films.

When reference in this specification or in the claims which are a part hereof is made to "blackand-white films, it is understood that such terminology is used with the meaning common in the motion picture art. Such black-and-white" films may be colored by tinting or toning or any other similar process, whether carried on as supplementary to the regular development and fixing or otherwise. Moreover, the term may be used to include films which are made upon a base which is colored ortinted; provided the emulsion used thereon is one of those ordinarily associated with the making of black-and-white images if used with an ordinary white or gray base. It will be understood, of course, that when it is desired to use color for the pictorial portion of the film, our process may be applied to that portion of the negative which is reserved for the symbols representing sound.

It will be noted in the subjoined claims that the step of moving the film is not in allcases specifically included, although, as well known to those skilled in the art, and as is stated herein, sound. is ordinarily recorded upon, printed upon, and reproduced from, a moving film. Such omission in' the claims of an obvious step is to avoid encumbering the claims with unnecessary words, since, wherever necessary, the inclusion of this obvious step will be understood.

The processes of the electrical recordation of sound upon a photographic film or similar light sensitive surface are of course well understood. The film or other light sensitive material is moved continuously at a. uniform speed and upon it, generally through a slot, a light is projected, varying in accordance with the amplitude of the sound waves which are being recorded' Thus there is imprinted upon the light sensitive surface a series of images the photographic density of which varies in accordance with the variations of the sounds which are being recorded. The resulting images may appear to the eye to be a series of lines of varying intensity. These lines in the negative indicate by means of greater density the nodes of the sound waves and by less density the anodes of the sound waves, or, in case of the use of photo-electric cells ofa certain less usual type to control the fluctuation of the light, the reverse is true.

As a matter of convenience, it is to the aboveindicated method of sound recordation that reference will most often be made. It will be read ily understood, however, that our invention is equally applicable to any form of sound recordation which depends upon the implantation of photographic images upon a light sensitive material, whether, for example, such images take the form commonly known as variable density or variable area or any other form.

Similarly it will be understood that the reproduction of photographically created sound records of any type depends upon the passage of light therethrough and its impingement upon material the resistance of which to an electrical current varies in accordance with the light thrown thereupon, this electrical current telephonically create ing sound waves. Consequently any lack of exactitude in the translation of the sound image into the photographic image will be reproduced in the translation of the photographic image back into the sound image, together with whatever additional inaccuracy or lack of clarity may exist because of the imperfections of this process of re-translation.

Polychromatic light, the use of which our in-' vention eliminates, causes much of this inexactitude and many of these imperfections.

Figure 1 illustrates in a much exaggerated form the edge diffraction which is caused by passing polychromatic light through a narrow slot of the In this and many of the following drawings, for convenience we show the light as a straight line such as I. It will be understood that, except as definitely stated, we do not limit ourselves to an optical system of any particular nature. The light may be projected, by any suitable optical system, in the form of parallel, di= vergent or convergent light. If desired, a mirror or other reflecting element, not shown, may be employed behind the light source. This light in passing through the opening 3 in the aperture plate 4 is diffracted in accordance with the wave lengths of its component parts. Thus the infrared rays 6 and 6' show the maximum diffraction, the visible red rays 1 and I the next largest degree of diffraction, the yellow rays 8 and 8 a lesser difiraction, the blue rays 9 and 9' the least amount of difiraction of the visible rays and the ultraviolet rays ill and ID the least diffraction, the degree of difiraction of the sub-primary colors not being shown. I

As these rays of varying wave lengths fall upon the film 5, as is well illustrated in Figure 2 of the drawings, there are transverse bands of the light sensitive emulsion which are subjected to rays of different colors. Every light sensitive emulsion has verying degrees of sensitivity to diiferent colors. As a result of such varying sensitivity, while the entire portion of the emulsion between the lines H and II is acted upon with approximate uniformity by the white light, the bands from ill and Hi to 6 and 6', both inclusive, are acted upon in degrees varying according to the sensitivity to color of the particular photographic emulsion which is being used at the time. As a result the portions of the entire line or mass which lie between H and 8 and II and 6 respectively are lacking in uniform photographic density, the portion between H and II being of the photographic image which is bounded by such an edge is used to actuate a photo-electric cell in the reproduction of sound, what the auditor hears is likewise unclear, muddy and blurred. It will be readily recognized that any blurring of a recorded photographic image caused by such diffraction will result in a corresponding blurring of the sound which is reproduced therefrom. r

We have found that much of the difliculty in the past blamed generally upon difiusion", and even photographic grain, is in reality due to the lack of a correct photographic definition caused by fringing colors, which in turn are the result of diffraction as stated above.

It will be readily understood that the more narrowly the slot is restricted in size, the more pronounced will be such imperfections.

In Figure 3 we show diagrammatically one embodiment of our invention applicable to a sound recording system such, for example, as one which employs an immovable light supplied by an electric current varying in accordance with the amplitude of the sound waves to which a diaphragm is subjected.

In Figure 3, the intensity of the light at source I2 in operation is constantly varied in accordance with the amplitude of the sound waves which are being recorded. Any one of the many well known devices to accomplish such purpose may be employed, as for example a microphone l3 connected with any suitable type of current controlling device indicated generically as l3. Since the method of controlling the variations of the light source 52 in accordance with the sound waves is well known and forms no part of the present invention, it is neither described nor claimed.

The light i emitted by source 52, we pass through an appropriate color filter id, the slot 3 in the aperture plate t and on to the film 5. Since the optical system, and the method of feeding the film form no part of the present invention and since any of several well known optical systems and film feeding methods may be employed, we do not describe or claim them.

The exact filter to be used will depend upon the photographic characteristics of the emulsion selected. It will be readily understood that with the use of any monochromatic light all of the area of the film which is exposed or illuminated at the same instant will be of practically uniform density. For example, if we elect to employ light of approximately 4000 Angstrom units, we will use a filter I4 adapted to prevent the passage of all light other than such as will register between 9 and 9', inclusive, as shown in Figures 1 and 2. The image so created upon the film will have sharp demarcation along the lines separating band 9 from band 8 and band 9' from hand 8. That is, each illuminated or exposed area will be clearly and sharply defined and its so-called photographic contrast great. Irrespective of the type of monochromatic light employed, the sharpness or differentiation or contrast will be increased over-such as obtained with polychromatic light and the raggedness caused by the use of such light largely eliminated. It should be noted, however, that the relative excellence of the result will depend upon the selection of the wave length particularly appropriate to the photographic emulsion selected. In recent practice, in order to overcome difiiculties caused by the so-called grain of the emulsion, relatively slow emulsions, such as, for example, those of 120 according to the rating of Hurter and Drifiield, have been recommended for sound films. By the use of photographically active wave lengths, such as for example those in the vicinity of 4000 Angstrom units, we secure with such a slow emulsion in a relatively short period of exposure the same results as others secure in a much longer and hence impractical period of exposure.

It will be understood that instead of using rays of one wave length only, we may employ rays of a group of related wave lengths.

In carrying out our invention we may simultaneously record the images representing sound upon the same film as that upon which the images representing action are recorded. Or we may make records of each series of images upon dif-. ferent films and subsequently impose the images representing sound upon an unoccupied portion of the film bearing the original images representing'action. Or we may make separate record or negative films for the sound and action images and duplicate both such series of images upon different portions of one positive film.

If we use a common record or negative film for both sound and action images, as is shown for purposes of illustration herein, we may provide a camera lens CL through which light I from the action or scene being recorded is focussed through the aperture 3' upon the film ii. It will, of course, be understood that a certain portion of the film is reserved for the action images and another separate portion for the sound images, the respective apertures 3' and 3 being so designed as to direct the light beams l and 8' upon the appropriate portions of the film.

In those cases in which the sound and pictorial records are simultaneously'placed upon the same film, we may prefer to use an emulsion rated at between 120 and 200 according to the scale of Hurter and Drifiield. An emulsion of a speed of 180 upon that rating ma: be taken for purposes of illustration.

For an emulsion of such a speed, with a latent image of the sound record produced by monochromatic light, as for example that of approximately 4000 Angstrom units, and the pictorial portion produced by polychromatic light, we prefer to use glycin, known as gamma oxyphenyl or as gamma oxyphenyl-amido-acetic acid, as the developing agency. Under such conditions, glycin will produce the necessary contrast in the sound image and at the same time time build up the half tones of the action image. It will be readily understood by those skilled in the art that for pleasing results in reproduction the sound images require great contrast and the action images full gradation. If, however, polychromatic light is used for the sound images, the glycin development would tend to reduce the contrast in the sound images to a point which will result in unsatisfactory reproduction. If a hydrochinone developer is used, the sound image made with light of a wave length of 4000 Angstrom units would be satisfactory but the pictorial image, which is of course always recorded by polychromatic light, would be unpleasantly harsh. If a hydrochinone developer is used with a sound image made by polychromatic light, a period of development is necessary in order to secure proper contrast in the sound image which will still fur-- ther increase the unpleasant harshness of the pictorial image.

The use of glycin is desirable also because it tends to reduce the grain. As is well known in the art, a slow emulsion has less grain than a more rapid one. Hence we prefer to use as slow an emulsion as is consistent with the demands of the pictorial image. Only with the use of mono- In glycln development, the following stock solution may be prepared:

Water, H2O ounces Sodium sulphite, NazSOa, anhydrous grams 360 Glycin, CsHiCHNHCHsCOOH do 120 Sodium carbonate, NazCOs, anhydrous grams 36 The chemicals should be disssolved in the above order. The water should preferably be of a Fahrenheit temperature between and degrees.

. For use with the emulsions of the speed stated above, such stock solution may be diluted at the ratio of one part 'istock solution and three parts water. The film may be developed for thirty minutes, preferably at about .65'degrees Fahrenheit. After such development, the usual steps of washing, fixing, and final washing may be taken. g

We prefer to keep the film totally immersed during the entire period of development in order to minimize oxidation fog. We have found that the elimination of such fog is an important item aosaaoi is a developer which produces a minimum of such fog, but to prevent the possible formation of such fog, we may prefer to use a bath of pinakryptol green, in a dilution of one part to five thousand parts of water, before the development as by the use of glycin.

It will be understood that we do not restrict ourselves to the particular formulae, chemicals, or emulsion speeds stated above, but that we state the same for purposes of illustration.

For purposes of further illustration, it may be assumed that we wish to make a combined sound and pictorial record of waves breaking upon the shore of the sea. in order that we may secure full color and gradation values, we may prefer to use an emulsion having the color sensitivity commonly known as panchromatic together with a filter for the pictorial portion of the film. Such a filter may be of a yellow color and of the type commonly known in the photographic art as K3. For the sound image, we may prefer to use a light of approximately 4000 Angstrom units because such a light, in combination with a panchromatic emulsion, produces great contrast. The polychroinatic light, modified as is well known in the art by the K3 filter produces an image which is soft and pleasing. Glycin development of such a film gives satisfactory results in both portions. In this case, however, with the use of panchromatic film, we may prefer to use a preliminary bath of pinakryptol green diluted at the ratio of one part to four thousand parts of water.

For the purpose of still further illustration, it may be assumed that it is desired to produce a combined sound and pictorial film under conditions which require a fast emulsion. The action to be recorded, for example, may be rapid or light conditions poor and not subject to control as in a studio. An emulsion of a speed on the Hurter and Drifiield scale of over 450 may be chosen. Under such conditions, a monochromatic light of 4000 Angstrom units maybe too rapid in its action. In such cases, we prefer to use for the sound recordation a filter which will transmit light of a suitable wave length or group of wave lengths as, for example, any wave length or group of wave lengths between 4500 to 5800 Angstrom units, depending upon the particular emulsion employed. Thus we are enabled to give to the operator definite filters for use with definite emulsions, rather than depending upon adjustments in the field of the light source for the sound record.

It has been proposed in the past to make use of special emulsions which, after the images implanted thereon have been developed and rendered visible, have peculiar characteristics of permeability by or absorption of light waves of particular wave lengths in combination with the photo-electric cell of particular characteristics in a sound reproducing instrument. It will be understood that we use regular stock photographic films known as black-and-white, which can be readily and cheaply obtained throughout the world, choosing such films, however, in accordance with the purely photographic characteristics thereof which are useful for the particular purpose set forth in this specification. Our choice of an emulsion of a particular speed is conditioned by the photographic characteristics of the latent images which can be implanted thereon by the use of light of a particular wave length, and the photographic characteristics of the visible and stable images which can be developed from such latent images. Although our invention can be applied to those types of apparatus in which separate films are employed for the sound and pictorial records, it is also equally applicable to those types of apparatus in which one film is used to carry both such records. It will be readily understood that such a single film bearing both such records must be chosen, exposed, developed, duplicated and projected in accordance with all the requirements of both such records. As is made clear throughout this specification, our method is so adapted to create a single film which bears both types of records thereupon.

Figure 4 diagrammatically shows our invention as applied to the reproduction of sound. The light i from a constant light source it passes through the appropriate color filter id, the slot 3 of the aperture plate i and the him 5, and impinges upon the photo-electric cell it of its'equivalent, which actuates the sound producing device 28 through the control element it. Since the optical system, the method of film feeding, the light sensitive electrical element and the sound producing device and its control form no part of the present invention and are well known in the art, they are not further de scribed or claimed. Light i is shown as passed from a lamp house Ll-I through a projection lens L and gate 3' and the film 5 and upon a screen S, as is well understood in the art.

The same considerations apply to the effect of light upon light sensitive electrical elements as upon the light sensitive emulsions. Mixed or polychromatic light impinging upon a photoelectric cell causes variable and untrue sound reproduction, since the photo-electric cell is differently responsive to each color. The results obtained by our use of monochromatic light for translation of light into sound are analogous to or the same as those described above for the translation of sound into light.

Another factor improving reproduction and recordation renders the use of monochromatic light for sound translation superior to any means heretofore employed. As is well known in the rt, the sensitivity of photo-electrical elements commonly varies both in accordance with the color of light and its intensity. Thus any change in voltage or temperature of the theoretically constant light source it may cause a color change as well as an intensity change, varying white light from red through yellow to in many cases even blue. The photo-electrical element is affected by such change in color as well as by the reduction in intensity. Later we describe means for removing one cause of change in color but it is obvious that better results are obtained by the removal by the use of monochromatic light of one of the variants so described.

It is apparent that the ability so to record tonal variations in very great detail and almost microscopic size will render possible a vastly increased range of tonal recordation and likewise a notable improvement in the detail of recorded sound.

It is also apparent that the increased intensity of light available for delivery at the surface of the film 5 through the means described will render possible the use of whatever loss photo graphically active rays of light and photographically slower emulsion which may be deemed desirable because of the so-called grain or other photographic difliculties, all of which above advantages, methods and means are such skilled in the art without further description or explanation in detail.

Figures and 6 illustrate diagrammatically the application of our invention to printing or duplicating apparatus.

The negative film at and the positive film 55 may be fed in any manner well known in the art, as through a common gate or through separate gates with an optical element intervening.

10' Figure 5 shows a gate ill having an aperture 62 including a space left unimpeded for the pic torial images on frames 36 of the film and a light filter til adapted to cover the area opposite which the sound images 39 of the film are fed. The

negative therefor is seen as traveling through positive film 65, which may if desired be of a size smaller than that of the negative.

It will of course be understood that the filter 134 may if desired be placed in the gate through which the positive him is fed. It will also be understood by those skilled in the art that as illustrated and described at length in our parent application Serial Number 600,322, filed March 21, 1932, as divisional from our said parent case, we show separate elements for the simultaneous printing of the sound image and the light image or for successive printing of thetwo images from the one negative upon one positive, such print ing exposure taking place successively.

The type of gate shown for purposes of illustration only herein is best adapted for printing from a duplicate negative which has been go timed" so that fluctuation of the printing light for the picture area to compensate for dinering densities is not required. Itwill be understood, however, t any desired form of printer may be used to carry out our invention. It will 45: also be understood that the form. of gate shown in Figure 5 may be used for recording or repro-- duction with the sound aperture covered by the filter dd conventionally spaced from the picture aperture.

The necessity of a hard contrasting image for the sound portion or the film has been emphasized above. Such images, however, in the pictorial portion of the film generally prove very unpleasant. It will be thus seen that our invention makes it possible to use whatever type invention by means of the use of ultraviolet light, we employ any suitable light source encased in quartz, or a. light source which will emit'visible and ultraviolet light under normal atmospheric conditions, such as, for example,

the electric amend the so-called Nernst lampl:

carrying out our invention inaccordanccaocaser with this exemplification, we use a light source id of some such type as we mention above in.

the aperture plate which is illustrated and claimed in our said parent application.

To secure improved and stable translation of sound images into light images, the theoretically constant light source maybe maintained at a point which is actually constant, or approximately constant, as is illustrated, for example, in Figure 7 of the drawings. Obviously the difficulties caused by the change in color of the light caused by the fluctuations oi the light source are removed b." the use of monochromatic light. A further embodiment of our invention prevents material change in light intensity, such changes causing analogous difilculties.

A common cause of change in intensity of the theoretically constant light source is found in temperature changes which decrease or increase the degree of incandescence of the light element. The common expedient of warming the light source by turning on the current in advance of its use does not meet the dimculties caused by later changes in temperature caused by conditions which later develop. We have found that the opening of a door or window in a room in which apparatus is being used will change the visible characteristics of the light. The means shown for example in Figure 7 definitely controls the heat of the theoretically constant light source. 7

A light source shielded and controlled as is here'set forth may be used as described in any or all of the previously described exemplifications of our invention. The arrangement herebelow described isof particular usefulness under any conditions under which an approximately constant light source is desired. Broad claims to this phase of our invention will be found in our parent application.

In one embodiment of our invention, we may place the light source it, which for example may be an incandescent globe of any desired type, in a chamber with double walls such as it and H, and preferably with an air space l2 between them. Fresh air is forced into this chamber 12 .by a fan 13 rotative upon a shaft it to which is attached a. pulley l5, and such air takes I the direction shown by the arrows. The pulley may be driven in any desired way, not shown. Through the opening I6 past the bafiie plate I1 the fresh air is directed into the inner lamp chamber. The wall it being preferably-of a heat conductive material, the fresh air, whileconsiderably cooler than the body of air in the chamber, is not of a. temperature sufliclently low to cause a drop in the incandescence of the lamp.- The heated air leaves the chamber through the vent 18 in the top, which is protected'by bafiie plates, not shown, as is .well known in the pro jection art, to prevent the escape of objectionable light. This construction per se 'isclalmed in our parent application.

Under some conditionathe. i'an 13'may beldis.

with, sufljcient circulationof air being-i m,-

obtained by the heat generated within the chamber.

Light is passed from the source it through the optical element 19 which may form the window, as it were, of the lamp chamber. Such optical element may be a plate of plane glass or quartz, merely to complete the enclosure of the chamber, or it may be a suitable condensing lens or filter. A mirror or other reflecting surface 80 may be provided.

In order positively to maintain the lamp l2 at a given point of incandescence by holding the temperature of the chamber at a predetermined point, a thermostatic element 3i may be provided which, through an appropriate electrical means, controls the amount of current which is permitted to flow into the heating units 82 which may be placed within the chamber.

The thermostatic control of the circuits of the heating units 82 may be accomplished in any of various well known ways. For example, the thermostatic element 8i may be in circuit with the magnetic element 83 which determines the movement of the wiper arm iii! so that it places more or less of the'resistance 85 in circuit with the heating elements 82, thusdetermining their activity.

It will be understood that we do not limit ourselves to this type of control unit and refer to it merely for purposes of illustration.

In order to compensate for changes in incandescence of the light source which might be brought about by changes in the temperature of the lamp chamber, or lamp house as it is generally termed in the motion picture art, we may regulate the amount of current reaching the lamp in accordance with the temperature of the immediate vicinity of the lamp. Such means may be employed independently of the heat maintaining means just described, or in conjunction therewith. For simplicity, we illustrate this phase of our invention in Figure '7, which also illustrates such heat maintaining means.

A thermostatic element 86 may be provided which controls the amount of current which is permitted to fiow into the light source l2. As is later set out in further detail, such control is exercised within restricted limits. The thermostatic control of the circuit supplying the source I2 may be accomplished in any of various well known ways. For example, the thermostatic element 86 may be in circuit .with the magnetic element 81 which determines the movement of the wiper arm 88 so that it places more or less of the resistance 89 in circuit with the light source l2. The range within which the current reaching the lamp is permitted so to fluctuate is very small.

' When a light source, particularly an incandescent light source, is operated reasonably near its point of optical efliciency, a relatively small fluctuation in the current reaching such source will have relatively great effect in the intensity of its light output. It will be understood that since uniformity and not intensity is desired, it is prefenable to burn the lamp at a point well below that at which injury to the filament is likely. We prefer that the maximum current permitted to reach the lamp by the resistance 89 be sufficiently restricted so that even when the filament is cold such maximum current will not be dangerous to the life of the filament.

As an additional safeguard, to prevent overloading of the circuit supplying the light source, we may place in such circuit an automatic circuit breaker 90, orother similar device, or the light source l2 may be fed direct from a battery on the line. This control element will positively prevent any amount of current, over the predetermined maximum, reaching the light source ii.

In those cases in which the heating elements and the means for the control of the circuit of the light source are jointly used, it will be readily understood that the usefulness of the latter means generally will be greater in the early stages of any period of operation. After the temperature of the lamp chamber has been brought to the desired point, it will generally be so maintained by the heating elements alone.

It will be readily understood by those skilled in the art that the joint operation of these two means involves no conflict. From the time of beginning operation until the temperature of the lamp chamber reaches the predetermined point, the thermostatic element 8! will operate gradually to increase the amount of resistance 35 in circuit with the heating elements 82 and so render them less and less active. From that point outwardly, the fluctuations-of current in the circuit feeding the heating elements 82 will be such as are necessary to maintain that predetermined point of temperature. It is understood that the ventilating device such as heretofore described when the heating units 82 are entirely inactive will prevent the temperature of the chamber from reaching a point higher than the predetermined point.

When operations begin, all resistance 89 will be out of the circuit feeding the light l2, it if desired being protected against overloading as by the element 90. As the temperature of the chamber increases, the amount of such resistance-89 in circuit with the light source l2 gradually increases until the entire amount is in circuitwhen the temperature reaches the predetermined point.

Should such temperature rise still further, as is not contemplated owing to the above described ventilating system, there would be no change in the amount of such resistance 89 in circuit. Should such temperature fall, the amount of resistance 89 would be decreased until the light source l2 receives the entire amountof current delivered from the line as through the protective device 90. The range of the resistance 89, it will be understood, is carefully limited in accordance with the closely limited range in which current fluctuations occur.

It will be understood by those skilled in the art that while our invention is of particular usefulness under conditions under which the sound and pictorial images are simultaneously recorded, duplicated, and reproduced, it is of great usefulness when the sound and pictorial images during a portion of the entire process are handled separately and successively, later being combined.

It will thus be apparent that the method and construction above described provide extremely simple means whereby sound waves may be accurately and efiectively translated into photographic images.

Other advantages have been referred to throughout the specification from which it becomes apparent that diiferent embodiments of the invention may be made within the scope .of the inventive disclosure hereof.

-We claim:

1. The method of recording sound and pictorial images upon a single light sensitive film which consists in varying monochromatic light in accordance with the soundwiiich'is being recorded,

lengths to vary in accordance with the'sound to for implanting thereupon images representing such sound, using polychromatic light for implanting thereupon such pictorial images, and concurrently rendering both of such images stable and visible.

2. The method of, recording sound and pictorial images which comprises exposing one portion of a light sensitive film to light which, varies in accordance with the sound which is being recorded for implanting thereupon images representing such sound and limiting such light to ultra violet, exposing a different portion of said film to polychromatic light for implanting pictorial images thereupon, and concurrently rendering both of such images stable and visible.

3. The method of recording sound and pictorial images which consists in exposing one portion of a light sensitive film to light of a wave length of approximately 4000 Angstrom units which varies in accordance with the sound which is be'mg recorded'for implanting thereupon images representing such sound and exposing a difierent portion of said film to polychromatic light for implanting pictorial images thereupon and concurrently rendering both of such images stable and visible.

4. The method of recording sound and pictorial images which comprises passing light through a slit and upon light sensitive material, varying such light in accordance with the sound to be recorded, limiting such light to rays which vibrate at substantially the same rate thereby minimizing the efiect of chromatic dispersion caused by said slit, utilizing polychromatic light for implanting upon another and selected portion of said light sensitive material such pictorial images,

-.and polychromatic light for implanting thereupon such pictorial images, concurrently rendering both of such images stable and visible, and concurrently passing light through both sets of such images whereby such sound and pictorial images are concurrently reproduced.

-6. The method of recording and reproducing sound and pictures which comprises exposing certain selected portions of a light sensitive film to the action or objects which it is desired to record for visual reproduction and exposing other selected portions thereof to monochromatic light which varies in accordance with the sound which it is desired to reproduce for audible reproduction concurrently with such visual reproduction, rendering the latent images so produced in both such portions stable and visible, and simultaneously reproducing both of said portions by concurrently passing monochromatic light through said images representing sound and polychromatic light through said images representing action or objects whereby the images of action or objects and the images of sounds are concurrently reproduced.

'7. The method of recording sound which consists in taking a light sensitive film, causing light which falls within a predetermined range of wave be recorded and to fall upon said light sensitive filmthereby producing latent images, developing 75-, the latent images so produced, using polychromatic light to record upon the same light sensitive film images of objects or things which itis desired to reproduce concurrently with the reproduction of such sound, simultaneously developing the latent images so produced, printing said film by passing light of a selected wave length through said images representing sound and upon a second light sensitive film thereby producing latent images and by passing polychromatic light through said images representing objects or things and upon said second light sensitive film thereby producing latent images, simultaneously developing the latent images so produced upon said second mentioned film, projecting a constant light of a selected wave length through said stable and visible images representing sound upon said second mentioned film and upon a material the electricalcharacteristics of which vary in accordance with said light impinging thereupon and simultaneously passing polychromatic light through said images representing objects or things whereby said sound and said objects or things which have'been previously recorded are simultaneously reproduced.

8. The method of recording sound which consists in taking a light sensitive film, causing light which falls within a predetermined range of wave lengths to vary in accordance with the sound to be recorded and to fall upon said light sensitive film thereby producing latent images, developing the latent images so produced, using polychromatic light to record upon the same light sensitive film images of objects or things which it is desired to reproduce concurrently with the reproduction of such sound, simultaneously developing the latent images so produced, printing said film by passing light through said images representing images representing objects or things whereby said sound and said objects or things which have been previously recorded are simultaneously reproduced.

9. The method of recording sound which consists in taking a light sensitive film, causing light which falls within a predetermined range of wave lengths to vary in accordance with the sound to be recorded and to fall upon said light sensitive film thereby producing latent images, developing the latent images so produced, using polychromatic light to record images of objects or things which it is desired to reproduce concurrently with the reproduction of such sound, developing the latent images so produced, printing said film by passing light of a selected wave length through said images representing sound and upon a second light sensitive film thereby producing latent images and by passing polychromatic light through said images representing objects or things and upon the same light sensitive film thereby producing latent images, simultaneously developing the latent images so produced upon said second mentioned film, projecting light of a selected wave length through said stable and visible images representing sound upon said second mentioned film and upon material the electrical characteristics oi which vary in accordance with said light impinging thereupon and simultaneously passing polychromatic light through said images representing objects or things whereby said sound and said objects or things which have been previously recorded are simultaneously reproduced.

10. The method of recording and reproducing sound and pictorial images which consists in exposing a selected portion of a light sensitive film to light of a selected wave length which varies in accordance with the sound which is being recorded and in exposing other selected portions of said film to polychromatic light for recording thereupon said pictorial images; developing both sets of latent images so produced, printing said film by passing light therethrough and upon a light sensitive film and developing the latent images so produced upon said second mentioned film, and thereafter projecting a constant light through the portion of said second mentioned film which bears said sound images, the source for said light being positioned in a chamber the temperature of which is maintained at a predetermined level, and upon material the electrical characteristics of which vary in accordance with the light impinging thereupon, and simultaneously projecting polychromatic light through saidpictorial images whereby said pictorial images and said sound images are simultaneously reproduced.

11. The method of recording and reproducing sound and pictorial images which consists in exposing certain selected portions of a light sensitive film to light of a selected wave length which varies in accordance with the sound which is being recorded, exposing other selected portions of said film to reproduce thereupon pictorial images, simultaneously developing both sets of latent images so produced, printing said film by passing light therethrough and upon a light sensitive film and developing the latent images so produced upon said second mentioned film, and thereafter projecting a constant light through the portion of said second mentioned film bearing said sound images, said light being maintained at a predetermined level of such characteristics that the light emitted has wave lengths falling within a predetermined range, and upon a material the electrical characteristics oi! which vary in accordance with said light impinging thereupon, and simultaneously passing polychromatic light through the portion of said second mentioned film bearing said pictorial images and upon a screen whereby said sound and pictorial images previously recordedare reproduced.

12. The method of recording and reproducing sound and pictorial images which consists in exposing certain selected portions of a light sensitive film to light of a selected wave length which varies in accordance with the sound which is being recorded, exposing other and relatively ditierently placed portions of a film to reproduce thereupon pictorial images; developing both sets of latent images so produced, combining both of said sets of images upon another light sensitive film and developing the latent images so produced upon said second mentioned'film, and

thereafter projecting light of wave lengths falling within a predetermined rangeth'rough the portion of said second mentioned film bearing said sound images, and upon a material the electrical characteristics of which vary in accordance with said light impinging thereupon and passing polychromatic light through the portion voi said second mentioned film bearing said pictorial imagesand upon a screen whereby said sound and pictorial images previously recorded are reproduced.

13. The method of recording and reproducing sound and visible images of objects or things which consists in projecting light of a selected wave length which varies in accordance with the sound which is being recorded through a slot and thereafter through a positive lens and upon certain selected portions of a light sensitive film; exposing other selected portions of said light sensitive film to polychromatic light for the creation thereupon of latent images of objects or things; developing both sets of latent images so produced; printing said film by passing light through both oi! said portions and upon a light sensitive film and developing both sets of the latent images so produced upon said second mentioned film; thereafter projecting a constant light of a selected wave length through a slot and through those portions 0! said second mentioned film which bear images representing sound and thereafter through a negative lens and upon a material the electrical characteristics of which vary in accordance with said light impinging thereupon; passing an electrical current through said material and using the variations so produced to reproduce the sound previously recorded; and simultaneously with-said previously defined projection prdjecting polychromatic light through said visible images and upon a screen whereby said sound and said visible images previously recorded are simultaneously reproduced.

14. The method of recording and reproducing sound and visible images of objects or things which consists in projecting light 01' a selected wave length which varies in accordance with the sound which is being recorded upon certain selected portions of a light sensitive film; exposing other selected portions of said light sensitive film to polychromatic light for the creation thereupon of latent images of objects or things; developing both sets of latent images so produced; printing said film by passing light through both of said portions and upon a light sensitive film and developing both sets of ,the latent images so produced upon said second mentioned film; thereafter projecting light of a selected wave length through those portions of said second mentioned film which bear images representing sound and upon a material the electrical characteristics oi which vary in accordance with the light impinging thereupon; passing an electrical current through said material and using the variations so produced to reproduce the sound previously recorded; and simultaneously with said previously defined projection projecting polychromatic light through said visible images and upon a screen whereby said sound and said visible images previously recorded are simultaneously reproduced.

15. The method of recording and reproducing sound and pictorial images; which comprises exposing one portion of a light sensitive film to light of a selected wave length which varies in accordance with the sound which is being recorded; and exposing a different portion of said film to the action or objects which it is desired to record and reproduce as pictorial images; developing concurrently both such series of latent images so produced; duplicating said film by passing light of a selected wave length through the portion of said film which bears such sound images and upon one portion of a second light sensitive film and passing polychromatic light v through the portion of said film which bears such pictorial images and upon another portion of said second film; developing concurrently the latent images so produced upon said second film; and thereafter projecting constant light of a selected wave length through the portion of said second film which bears said sound images and upon a material the resistance of which to an electrical current varies in accordance with the light impinging thereupon whereby sound corresponding to that sound which has been so recorded is reproduced and projecting p0lychromatic light through said other portion of said second film bearing said pictorial images thereupon and upon a screen whereby said pictorial images are reproduced.

16. The method of recording and reproducing sound and pictorial images which comprises exposing one portion of a light sensitive film to light of a selected wave length which varies in accordance with the sound which is being re-; corded; and exposing a different portion of said film to action or objects which it is desired to record and reproduce as pictorial images; developing both such series of latent images so produced; duplicating said film upon a second film; developing the latent images so produced upon said second film; and thereafter projecting constant light of a selected wave length through the portion of said second film which bears said sound images and upon a material the resistance of which to an electrical current varies in accordance with the light impinging thereupon; whereby sound corresponding to that sound which has been so recorded is reproduced and projecting polychromatic light through said other portion of said second film bearing said pictorial images thereupon and upon ascreen whereby said pictorial images are reproduced.

17. The method of recording an reproducing sound and pictorial images which omprises exposing one portion of a light sensitive film with an emulsion of a speed between and 200 according to the rating of Hurter and Driffield to light of a wave length of approximately 4000 Angstrom units which varies in accordance with the sound which is being recorded; and exposing a different portion of said film to action or objects which it is desired to record and reproduce as pictorial images; developing concurrently both such series of latent images so produced; duplicating said film upon a second film; developing the latent images so produced, upon said second film; and thereafter projecting constant light through the portion of said second film which jgbears. said sound images and upon material the resistance of which to an electrical current varies in accordance with the light impinging there'- upon; whereby sound corresponding to that sound which has been so recorded is reproduced and projecting light through said other portion of said second film bearing said pictorial images thereupon and upon a screen whereby said pictorial images are reproduced.

CARL LOUIS OSWALD. WARREN DUNHAM FOSTER.

CERTIFICATE OF ,CORRECTION.

Patent No. 2,055,261. September22, 1936 CARL LOUIS OSWALD, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, second column, line 31-32, for "sesure" read secure; page 4, second column, lines 65 and 58, in the table, for "grams" read grains; page 5', second column, line 20, for "of" read or; and that the said Letters Patent should be read with these corrections therein-that the same may conform to the record of the case. in the Patent Office.

Signed and sealed. this 16th day of February, A.D. 1937.

' Henry Van Arsdale ISeal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 2,055,261. September 22, 1936 CARL LOUIS OSWALD, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, second column, line 31-32, for "sesure" read secure; page 4, second column, lines 55 and 58; in the table, for "grams" read grains; page 5, second column, line 20, for "of" read or; and that the said Letters Patent should be read With these corrections thereinthat the same may conform to the record of the case in the Patent Office.

Signed and sealedv this 16th day of February, A.D. 1937.

Henry Van Arsdale fseal) 1 i 4 Acting Commissioner of Patents. 

